Vacuum-tube circuits



Sept. 1, 1925. 1,552,219

G. G. MERCER VACUUM TUBE CIRCUITS Filed April 2.3. 1220 inx/e nboi-"iGeorge Mercer,

flaw/ i His Attorney-- Patented Sept. 1, 1925.

UNITED "STATES V A 1,552,219 PATENT OFFICE.

oEoaoE GLENN MERCER, or SCEENEGTAIDY, nEw YoEx', assionon. T0 GENERALELECTRIC COMPANY, A CORPORATION or NEW YORK.

VACUUM-TUBE CIRCUITS.

Application filed April 23, 1920. Serial No. 375,976.

If an electron discharge device comprising an electron emitting cathodeand an anode enclosed in an evacuated receptacle.

has a source of potential connected between cathode and anode, a currentwill flow between cathode and anode which is carried.

by. means of electrons emitted from the cathode. The current flowingbetween the electrodes may be controlled ,or varied in amplitude bymeans of a magnetic" field set up in the receptacle in a direction atright angles to the electrostatic field between the electrodes. Tocontrol the current in this way requires a magnetic field ofconsiderable magnitude, that is, no variation will be produced in thecurrent-unless a magnetic field of a predetermined stren th is set up inthe space between the electro es.

When, however, a magnetic field of the required strength is set up inthe space between the electrodes a small variation in the strength ofthis magnetic field will produce a large variation in the strength ofthe current flowing between the electrodes. In the operati n of suchdevices in the past it has been cus mary to provide a separate source ofcurrent for producing a constant magnetic field of such a value that avariable magnetic field superimposed thereupon will produce the desiredchanges in the current. This constant magnetic field is usually termedthe polarizing field.

' The object of my invention is to eliminate the necessity for the useof a separate source of current for furnishing the polarizing field andto permit of the production of this polarizing field by means of theelectron current flowing between the cathode and anode.

In carrying my invention into effect I cause the current which flowsbetween the electrodes to pass through a coil or coils surrounding thetube. Altho in the 'usual operation of the device this current is causedto vary, I have found that by shunting these coils by means of acondenser of i proper size; for bypassing the variable component of thecurrent in the circuit a substantially constant current will flowthrough the coils and as a result a polarizing field of substantiallyconstant value will be produced.

The novel features which I believe to be characteristic of my inventionare set forth 'with particularity in the appended claims.

My invention itself, however, will best be understood by referenceto thefollowing description taken in connection with the ac companyingdrawings in which Figs. 1, 2

and 3 illustratediagrammaticallythree dif ferent' circuit arrangementsin w vention may be. employed.

As indicated in Fi 1, an electron discharge device is emp oyedcomprising an oh my inevacuated receptacle 1, which is preferably oftubular form and which contains a filamentary cathode 2. and an anode 3of cylmdric'al form surrounding the cathode.

A source of current 4 is connected tov the two terminals of the cathode2 for heating it to incandescence to cause it to emit electrons forcarrying. current across the evacuated space between the two electrodes.An external circuit between electrodes 2 and 3 includes a source ofdirect current 5, inductances represented conventionally at 6 and 7 butwhich actually are wound around the receptacle 1, and an inductance 8and a variable tuning capacity 9 in shunt to in du'ctance 8. Inductances6 and are shunted by a condenser 10. 'The current which flows betweencathode 2 and anode 3, through coils 6 and 7, produces a constantmagnetic field in the space between the electrodes which is in adirection parallel to the axis ofthe tube or at right angles to theelectrostatic field between the electrodes. Coils 6 and 7 and source 5are so propor-' ti'oned that this constant magnetic field will have apredetermined desired value. The coil 8 is coupled to a coil 11 inseries with the antenna 12,. and a second coil 13, which is also inseries with the antenna, surrounds the receptacle 1. This coil 13produces a second magnetic field in receptacle 1 which sired in thereceptacle 1.

is bypassed through condenser 10. As a result, the current flowing incoils 6, 7, will be substantially constant and-therefore will maintainthe constant polarlzlng field de- In Fig. 2 I have shown anothermodification of my invention in which devices of the type in questionare emplo ed as'amlifiers. In this case the current w ich is to eamplified is supplied to the coil 14 which surrounds the receptacle '1and the magnetic field produced by the current to be amplified producescorresponding variations in the current through the device. In lthiscase, as in Fig. 1, the variable component of the current through thedevice is bypassed through the condenserlO and the current flowingthrough the coils 6 and 7 is substan' tially constant. The variable comonent of the current in the plate circuit 0 the first device is suppliedby means of a transformer 15 to the input coil 16 of a second device 17,which is connected up in a similar manner. The variable component in theplate circuit of this second device is in turn impressed by means oftransformer-18 upon the output circuit 19, which may contain suitabledevices for giving an indication of the amplified current or may supplyamplified current in the input circuit of still another device as may bedesired. The input circuit of the second device 17 may be tuned by meansof a variable condenser 20 if desired.

The arran ement shown in Fig. 3 is similar to that shown in Fig. 2 withthe exception that the entire current in the plate circuit of the firstdevice is supplied to the input coil 16 of the second. Tn this case asin the preceding case, the input circuit of the second device may betuned by means of the condenser 21. I have indicated in the platecircuit of the device 17 a transformer 22 for supplying the amplifiedcurrent to the output circuit. This expedient may be employed if desiredas there is no advantage in supplying to the output circuit of thelastdevice the direct current component of a plate current.

While I have indicated and described only three circuit arran ements inwhich my invention may be 'uti ized, it is apparent that a great varietyof modifications in the cirdevice comprising anv evacuated receptaclecuit arangenents employed 'as well as in the specific iorm of apparatusused may he made without departing from the scope of my invention as setforth in the appended claims. I

What -I claim as new and desire to secure by Letters Patent of theUnited States, is

1. The combination in an apparatus of the class described of an electrondischarge containing a cathode adapted to'emit electrons and an anode,an external circuit between said cathode and anode containing a sourceof current and means for producing by current flowing in said circuit asubstan-, tially constant magnetic field in the space between saidelectrodes.

2. The combination inpan apparatus of the class described of an electrondischarge device comprising an evacuated receptacle containing a cathodeadapted to emit electrons and an anode, an external circuit be tweensaid cathode and anode containing a source of current, an inductivewinding surrounding said receptacle and connected in said externalcircuit to receive current there from, means for varying the current insaid circuit and means for maintaining a substantially constant currentin said inductive winding. $5

3. The combination in an apparatus of the class described of an electrondischarge device comprising an evacuated receptacle containing a cathodeadapted to emit elec trons andan anode, an externai circuit bev100 tweensaid cathode and anode containing a source of current, an inductivewinding sur rounding said receptacle and connected in said externalcircuit, means for varying the current in saidcircuit and a condenser in105 shunt to said inductive winding for bypassmg the variable componentof the current in said external circuit.

4. The method of. operating an electron I discharge device having anelectron emitting cathode and an anode enclosed in anevacuatedreceptacle, which consists in applying a potentlal to saidelectrodes to produce a flow of current between said electrodes;producmg by means of current flowing between sald electrodes, asubstantially constant magnetic field between said electrodes in adirection substantially at right angles to the electrostatic fieldbetween said electrodes and producing a variable magnetic field whlch issuperimposed upon said constant magnetic field.

5. The method of operating an electron discharge device having anelectron emitting cathode and an anode enclosed in an evacuatedreceptacle which consists in applying a potential to said electrodes toproduce a flow of current between said electrodes, producing a variablemagnetic field in the space between said electrodes for varying thecurrent between said electrodes, and producing by means of a constantcomponent of the current between said electrodes 'a substantiallyconstant magnetic field in the space between said electrodes.

6. The combination inan apparatus of the type described of an electrondischarge device comprising a cathode adapted to emit electrons and acooperating anode, an external circuit between said vcathode and anodecontaining a source of current, means for varying the currentflo'wing insaid curcuit, and means for producing by current flowing in said circuita substantially constant magnetic field in the space between saidelectrodes. 1

7. The combination in an apparatus of the type described of an electrondischarge device comprising a cathode adapted to emit electrons and acooperatin anode, an external circuit between sa1d cathode and anodecontaining a source of current, means for varying the current flowing insaid circuit, an inductance included in saidcircuit, and means formaintaining a substantially constant current in said inductance, andproducing by such current a substantially constant magnetic field in thespace between said electrodes.

8. The combination in an apparatus of the type described of an electrondischarge device comprising a cathode adapted to emit electrons,- and acooperating anode, an external circuit between said cathode and anodecontaining a source of current, means for varying the current flowin insaid Circuit, an inductive windingincluded in said circuit, means formaintaining a substantially constant current in said inductive windingand therebyproducing a substantially constant ma etic field in the spacebetween said electro es, said means comprising a connection in shunt tosaid inductivewinding for by-passing the variable component of thecurrent in said external circuit. i

9. The combination in an apparatus of the type described of anelectrondischarge device comprising a cathode adapted to emit electrons,and a cooperating anode, an external circuit between said cathode andanode containing a source of current, means for varying the currentflowing between said cathode and anode, an inductive winding included insaid circuit, means for maintaining a substantially constant current insaid inductive winding and producing by such current a substantiallyconstant magnetic field in the space between said electrodes, said meanscomprising a shunt connection in the circuit between cathode and anodefor rent flowing between cathode and anode.

In witness whereof, I have hereunto set my hand.

GEORGE GLENN MERCER.

